Linear recliner assembly with threaded linear drive rod and rotatably engaged gear stop

ABSTRACT

A linear recliner assembly in use with a seat having a seat back pivotally engaged relative to a seat bottom. A housing exhibits a communicating interior between a first and second ends. A drive rod is supported in linearly displaceable fashion from the first end and is secured to the seat bottom. The second end pivotally engages the seatback spaced from its pivot point. A rotatable gear located at a fixed lineal position within the housing receives the drive rod in threadably inter-engaged fashion. A trigger mechanism pivotally secured to the housing exhibits a downwardly biased detent communicating through an opening in the housing to seat between succeeding teeth of the gear. A spring supported within the housing contacts the drive rod. Upon release of the detent, a reclining force applied to the seatback results in displacement of the housing against the drive rod to bias the spring. The spring influencing the drive rod in a reverse direction such that, upon release of said detent when the seatback is in the reclined position, the spring influences the seatback to reverse pivot to a returned upright position.

FIELD OF THE INVENTION

The present invention relates generally to a linear recliner assembly inuse with a recliner seat having a seat back pivotally engaged with aseat bottom. More specifically, the present invention discloses amanually operable recliner assembly including an exteriorly threadeddrive rod inter-engaged with one or more interiorly threaded androtating gear stop elements. The drive rod is displaced in a firstdirection within the assembly housing, consistent with a seat occupantphysically reclining the seat back, an inner end bushing secured to therod compressing against an interiorly positioned spring. Uponre-triggering the release of the gear stop elements, the compressedspring influences the drive rod in a reverse linear extending fashionfrom the housing, thereby influencing the seat back to a reversepivoting and upright position.

BACKGROUND OF THE INVENTION

The prior art is documented with examples of linear seat recliners. Asis further known, most such seat recliners require a power input inorder to cycle such as a threaded rod which influences a seat backpivotally connected to a frame location of a seat bottom.

Examples of such power linear seat recliner assemblies are set forth inU.S. Pat. Nos. 5,199,764 and 4,962,963, both to Robinson, and whichcontrollably adjusts the angular position of a seat back relative to aseat cushion. A master recliner mechanism includes an integrally mountedmotor, a slave recliner mechanism, and an actuator cable connecting theslave and master recliner mechanisms for transmitting torque from themotor to the slave recliner mechanism. The motor simultaneously driveseach of the recliner mechanisms, each of which having a threaded rodassembly interconnected to a transmission assembly for providing desiredspeed reduction and linear reciprocal movement of the rod.

Additional manual linear type seat recliners are known and include suchas that disclosed in Conroy U.S. Pat. No. 4,669,781 which teaches apolygonal cross sectional shaped rod pivotally connected to the seatback. A nut exhibits a generally fixed position relative to the seatcushion and threadably engages around the rod. The nut is movable tofirst and second angular positions relative to the rod such that, and inthe first position, the nut engages the rod at the threaded apices tolock the rod in position relative to the nut. Upon being rotated to thesecond position, the rod is released for adjusting the angular positionof the seat back.

Also shown in Pickles U.S. Pat. No. 5,582,461 is an infinitelyadjustable linear actuator which adjusts the relative position of tworelatively movable components of a vehicle seat. The linear actuatorincludes a rotatable element fixedly mounted about a threaded shaft.First and second moving members are mounted within a housing, disposedon opposite sides of an annular collar formed on the rotatable element.The moving members are movable between a first position in which theydisengage the rotatable element from bearing surfaces at opposite endsof the housing to form a high rotational resistance connectionpreventing rotation of the rotatable element and the intereconnectedthreaded shaft and a second position in which the moving members arespaced from the rotatable element to enable the rotatable element tomove axially into low resistance engagement with the bearings in thehousing to enable free rotation of the rotatable element and thethreaded shaft.

SUMMARY OF THE INVENTION

The present invention discloses a manually operable linear reclinerassembly in use with a recliner seat having a seat back pivotallyengaged seat bottom. More specifically, the present invention disclosesa manually operable recliner assembly including an exteriorly threadeddrive rod inter-engaged with one or more interiorly threaded androtating gear stop elements.

The linear recliner assembly is pivotally engaged relative to a seatbottom. A housing body exhibits a communicating interior between a firstand second ends. A drive rod is supported in linearly displaceablefashion from the first end and is secured to such as a frame location ofthe seat bottom. The second end pivotally engages the seat back at alocation spaced from its pivot point.

A rotatable gear is located at a fixed lineal position within thehousing and receives the drive rod in threadably inter-engaged fashion.A trigger mechanism is pivotally secured to an exterior of the housingand exhibits a downwardly biased detent communicating through an openingin the housing to seat between succeeding teeth of the gear. A springsupported within the housing contacts the drive rod. Upon release of thedetent, an external reclining force applied to the seat back results indisplacement of the housing against the drive rod to bias the spring.The spring influences the drive rod in a reverse direction such that,upon release of said detent when the seat back is in the reclinedposition, the spring influences the seat back to reverse pivot to areturned upright position.

Additional features include the housing exhibiting a central tubularportion with a first end cap through which slidably displaces the driverod and a second end cap which is pivotally mounted to the seat back. Asecondary housing includes a trigger support portion and slidablyinserts in coaxially fitting fashion within the central tubular portion,and in particular a linear extending recess associated with the centraltubular portion through which projects the trigger support portion.

A cable attachment bracket secures to the central tubular portion inproximity to the trigger mechanism and to which is mounted a fixed outersheath portion of a cable, with an inner translating portion extendingfrom the outer sheath and engaging a clip secured to an upper projectinglocation of the trigger mechanism. A pair of torsion springs are securedupon opposing sides of a pivotal axis defining support pin, thisextending crosswise through the trigger support portion and the triggermechanism. In this fashion, the detent is continually biased in downwardengaging direction with the rotatable gear teeth to restrain rotation ofthe gear to linear displacement of the drive rod, and unless the cableis triggered (such as by a remotely located lever) in order to move theseat back between the reclined and upright position.

Other features associated with the present design include such as theprovision of (eccentric) load supporting thrust bearings arranged oneither side of the rotatable gear, as well as a support bushingpositioned in end facing contact with a selected thrust bearing. Otherfeatures include a cylindrical shaped drive support portion secured toan end face of the rotatable gear, as well as an end bushing secured toan interiorly extending end of the drive rod, this including an exposedend face which biases against the extending coiled ends of thecompressible spring.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the attached drawings, when read incombination with the following detailed description, wherein likereference numerals refer to like parts throughout the several views, andin which:

FIG. 1 is an operational view illustrating the linear recliner assemblyfixedly secured at a forward end to a frame location of a seat bottom,and at an opposite rearward end to a lower-most reverse pivotinglocation of a pivotally secured seat back;

FIG. 2 is a rotated perspective view of the linear recliner assemblyshown in FIG. 1;

FIG. 3 is a partially transparent view of the linear recliner assemblyshown in FIG. 2 and further illustrating the interior arrangement of thelinearly displaceable threaded rod with end secured bushing, as well asthe rotatable and trigger released gear stops for permittingdisplacement of the rod relative thereto and in a compressing engagementwith the interior coil spring;

FIG. 4 is an exploded view of the linear recliner assembly;

FIG. 4A is a sectional exploded illustration of a selected thrustbearing reference along line 4A-4A of FIG. 4;

FIG. 4B is a rotated two dimensional view of the thrust bearingillustrated in exploded fashion in FIG. 4A and showing the central loadsupporting disk with annular arrayed and support bearings sandwichedbetween first and second cover portions;

FIG. 5 is a side plan view of the recliner assembly as substantiallyshown in FIG. 1; and

FIG. 6 is a cross sectional cutaway view of FIG. 5 and showing a fullyinwardly displaced position of the drive rod and resultant maximumcompressed condition of the interior coil spring corresponding to areclined position of the seat back.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the several illustrations, the present inventiondiscloses a manually operable linear recliner assembly in use with arecliner seat having a seat back pivotally engaged relative to a seatbottom. More specifically, the present invention discloses a manuallyoperable recliner assembly including, most broadly, an exteriorlythreaded and linearly displaceable drive rod threadably inter-engagedwith a stationary positioned and rotating gear supported within therecliner assembly and which is selectively permitted to rotate by anengaging trigger mechanism.

In combination with a biasing coil spring contained with the housing,relative linear motion of the drive rod relative to the housing (causedby a seat occupant manually reclining the seat back) results in thespring being compressed. Upon re-triggering the release of the gear inthe reclined position, the spring causes the drive rod to displace in anopposite direction, corresponding to an upright return position of theseat back.

Advantages associated with the present design include the ability toeffectively recline the seat back manually, while facilitating thecompressed spring force for returning the seat back to the uprightdesign position, this saving dramatically on the expense andrequirements of other powered seat variants. Additional advantagesinclude the high cycling capabilities of the system, this maintaininglie integrity of the design after repeated recline to upright returniterations. In this fashion, the construction of the manual reclinerassembly is such that it provides a durable assembly which can endurenumerous cycling requirements over a long life.

While not limited to any one type of application, it is fartherunderstood and envisioned that the linear recliner assembly can beincorporated into any type of seat design not limited to vehicularapplications, and in which seat back upright return is desired withoutrequiring additional physical input. Such applications can includeairline seats, as well as use in furniture and in addition tocontemplated vehicle uses.

Referring to FIG. 1, an operational view is illustrated at 10 the linearrecliner assembly fixedly secured at a forward end to a frame location 2of a seat bottom 4. A rotating coupling is illustrated at 6 mounted overthe fixed frame location 2, the coupling receiving the forward mountingend of the recliner assembly. Further illustrated at 8 is a generallylower-most extending location of a seat back, this being arranged aspaced distance from a pivot point 9 of the seat back, and such that,upon reclining of the seat back, the lower-most location will reversepivot (i.e. exhibit a rotating direction opposite to that of the upperseat back) in a force exerting direction towards the assembly 10. Inthis fashion, the linear recliner assembly is pivotally engaged relativeto a seat bottom at both the forward seat frame mounted coupling 6 andthe lower extending seat back location 8.

As further illustrated throughout the several views, a housing bodyexhibits a communicating interior extending between a first and secondends. More specifically, a central tubular portion 12 is provided with afirst end cap 14 secured over the first end of the central tubularportion 12, the first end cap exhibiting an end face located andcentrally positioned opening through which slidably displaces anexteriorly threaded (e.g. exhibiting such as a triple spiraling threadedprofile) drive rod 16. A second end cap 18 is secured over the secondend of the central tubular portion 12 and terminates in a pair of linearextending and spaced apart mounting portions, see at 20 and 22, thesealigning with mounting portions of the pivotal seat back mountinglocation 8. A mounting pin 24 (see FIG. 1) extends crosswise throughaligning apertures (see at 26 and 28 in each of FIGS. 2-4) defined inthe mounting portions 20 and 22 as well as an aligning aperture (notshown) in the seat back location 8 for pivotally mounting the reclinerassembly to the seat back as well as to the seat bottom.

A secondary (likewise cylindrical shaped) housing is provided at 30 (seeas best shown in FIG. 4) and includes a trigger support, illustrated asa pair of spaced apart and upwardly/linearly projecting bridge portions32 and 34. The dimensioning of the secondary cylindrical shaped housing30 is such that it is capable of coaxially and slidably inserting withinthe open end of the main central housing 12, the housing 12 furtherexhibiting a linear extending recess 36 (again FIG. 4) extending fromthe associated end for a distance and corresponding to the dimensionnecessary to seat the linear projecting dimension of the trigger supportportions 32 and 34.

A rotatable gear 38 (see as best shown in FIG. 4) is located at a fixedlineal position within the housing and receives the drive rod 16 inthreadably inter-engaged fashion, the gear 38 illustrating an innerannular wall (not shown) upon which a plurality of spiral threads areinscribed, these engaging such as the triple threaded exterior spiralprofile of the drive rod 16. As further shown, the gear 38 exhibits aplurality of outer peripherally and circumferentially extending teeth.

As best shown again in the exploded view of FIG. 4, as well thesectional exploded illustration of FIG. 4A and the rotated twodimensional view of FIG. 4B, a pair of (eccentric) load supportingthrust bearings 40 and 42 are arranged on either side of the stationarypositioned and rotatable gear 38. Each of the thrust bearings, as bestagain shown by thrust bearing 40 in FIGS. 4A and 4B, includes a centralload supporting disk portion 44 incorporating an annular array ofindividual bearings mounted thereto, the central disk 44 beingsandwiched between a pair of outer disk coverings 46 and 48.

Additional features shown include a support bushing 50 positioned in endfacing contact with selected thrust bearing 40 (see again FIG. 4) and sothat the support bushing 50 is seated in abutting contact with the firstend cap 14, with the threaded drive rod 16 projecting through aligningcentral apertures in the support bushing 50 and the end cap 14. Otherfeatures include a cylindrical shaped drive support portion 52, thissecuring to an end face of the rotatable gear 38. An end bushing 54 issecured to an interiorly extending end of the drive rod 16 (such as byfasteners including hex or pin screws, not shown, inserting in lateralprojecting fashion through mounting apertures 56).

A coiled spring 58 is seated within the central housing 12, proximatethe second end cap 18, and such that it biases against an end face ofthe end bushing 54. As shown in FIG. 4, a spacer washer 60 is sandwichedbetween the exposed face of the end bushing 54 and a terminating coil ofthe spring 58. Comparing the exploded view of FIG. 4 with the assembledand partially transparent view of FIG. 3 (as well as the cutaway lineart illustration of FIG. 6) the manner in which the inner workingcomponents of the recliner assembly are mounted within the housing isclearly shown.

A trigger mechanism is provided as a main body 62 exhibiting a generallyflattened planar shape and, as best shown in FIG. 4, includes a heightincreased forward portion 64 and a substantially planar rear underside66. The main body 62 is pivotally secured at an exterior of the housing,such as by aligning the body 62 between the pair of spaced apart andupwardly/linearly projecting bridge portions 32 and 34.

A pair of torsion springs are shown at 68 and 70, these being securedupon opposing sides of a pivotal axis established by apertured locationsin the forward portion 64 of the trigger body 62 and the portions 32 and34 (see again FIG. 4) and through which is inserted a support pin 65(FIG. 4) to pivotally support the trigger mechanism body 62 between thebridge portions 32 and 34 collectively defining the trigger support. Adetent 74 is provided as (without limitation) a “U” shaped rigid wireand which is secured to a rear of the main trigger body 62 in downwardextending fashion (as shown including the extending ends of the detent74 mounting in vertical passageways in the trigger body and such thatthe detent extends from the planar rear underside 66).

In this fashion, the detent 74 is continually biased in downwardengaging direction through the linear extending recess 36, and so thatthe interconnecting and crosswise extending end portion of the detent 74seats within a valley location established between any succeeding pairof gear teeth to restrain rotation of the gear 38, thereby preventingresultant linear displacement of the drive rod 16. Additional featuresinclude a cable attachment bracket 76 secured to the central tubularportion 12, the bracket 76 including an upward terminating cable mountportion 78 arranged in proximity to the trigger mechanism 62 and towhich is mounted a fixed outer sheath portion 80 of a cable.

An inner translating portion 82 extends from the outer sheath 80 andengages a clip 84 secured (such as by pins 86 in FIG. 4) to the upperprojecting forward location 64 of the trigger mechanism 62. As furthershown, the opposite extending legs associated with each of the torsionalsprings 68 and 70 include a first end biasing the bridge portions 32 and34 and a second end downwardly biasing the main trigger body 62. Theinner cable portion 82 is triggered (such as by a remotely located levernot shown) in a retracting direction toward the fixed outer sheath 80,in order to pivotally disengage the detent 74 from the gear teeth 38 tomove the seat back between the reclined and upright position.

In use, and upon release of the detent 74 from the gear 38, an externalreclining force applied to the seat back results in displacement of thehousing (e.g. central body 12 with end caps 14 and 16) against the driverod 16 (this resulting in an inwardly directed rotational totranslational force delivered by the lowermost seat back portion 8against the cylinder housing and as further shown by rotational arrow 88in FIG. 1). This results in the drive rod 16 displacing against (andinwardly) relative to the housing, to bias the coil spring 58 (see asfurther best shown in FIG. 6. In this manner, the spring 58 influencesthe drive rod 16 in a reverse direction such that, upon release of saiddetent 74 when the seat back is in the reclined position, the spring 58influences the seat back to reverse pivot to a returned upright position(again FIG. 1).

As previously explained, the drive rod 118 is displaced in the firstreclining direction within the assembly housing, consistent with a seatoccupant (not shown) physically reclining the seat back (i.e. by pushingagainst the seat back following triggering the release of the detent 74from the gear 38) and so that the inner end bushing 54 secured to thedrive rod 16 compresses against the interiorly positioned spring 58.Upon re-triggering the release of the gear stop elements, the compressedspring 58 acts as a reverse direction driving force, thereby influencingthe drive rod 16 in a reverse linear extending fashion from the housing,again in order to turn influence the seat back to a reverse pivoting andupright position.

Having described our invention, other and additional preferredembodiments will become apparent to those skilled in the art to which itpertains and without deviating from the scope of the appended claims.

1. A linear recliner assembly in use with a seat, the seat having aframe supporting a pivotal seat back relative to a seat bottom, the seatbottom including a rotating coupling exhibiting a threaded interior andwhich is mounted to a side location of the frame, the seat backincluding a lower most portion extending below a pivot about which theseat back rotates, said recliner assembly comprising: an elongate andthree dimensional housing having a communicating interior between afirst end and a second end of said housing; a drive rod supported inlinearly displaceable fashion within said housing, said drive rodextending from said first end and being threadably displaceable throughthe interior of the rotating coupling; said second end of said housingpivotally engaged to the lower most portion of the seat back; saidhousing further comprising a central tubular portion, a first end capsecured to a first end of said central tubular portion, said first endcap exhibiting a central opening through which extends said drive rod, asecond end cap secured to a second end of said central tubular portion,said second cap terminating in first and second spaced apart mountingportions and, upon aligning said mounting portions with the pivotallyengaged location of the seat back, a pin being received in laterallyinserting fashion for pivotally mounting said second end cap to the seatback; a rotatable gear located at a fixed lineal position within saidhousing and through which said drive rod is threadably inter-engaged; atrigger mechanism pivotally secured to an elevated exterior location ofsaid housing and exhibiting a downwardly biased detent communicatingthrough an opening in said housing to seat between succeeding teeth ofsaid gear; said central tubular portion further comprising a linearrecess extending from said first end, said trigger mechanism furthercomprising a secondary housing coaxially inserting within said centraltubular portion from said first end, said secondary housing furthercomprising a trigger support projecting from said linear recess; and aspring supported within said housing interior in contact with said driverod, upon release of said detent from said gear an external recliningforce applied to the seatback resulting in displacement of said housingagainst said drive rod to bias said spring, said spring influencing thedrive rod in a reverse direction such that, upon release of said detentfrom said gear when the seatback is in the reclined position, saidspring influencing the seat back to reverse pivot to a returned uprightposition.
 2. The invention as described in claim 1, further comprisingat least one torsion spring seated upon a pivot location establishedbetween said trigger mechanism and said trigger support, said springincluding an extending leg biasing said detent toward said gear teeth.3. The invention as described in claim 1, further comprising a cableattachment bracket secured to said housing in proximity to said triggermechanism, a cable exhibiting an outer sheath and which is affixed tosaid cable attachment bracket, an inner translating portion extendingfrom said outer sheath and engaging a clip secured to said triggermechanism.
 4. The invention as described in claim 1, further comprisinga thrust bearing arranged at each of opposite sides of said rotatablegear.
 5. The invention as described in claim 4, further comprising atleast one support bushing arranged in linearly positioned and end facingcontact with a selected one of said thrust bearings.
 6. The invention asdescribed in claim 5, further comprising a cylindrical shaped drivesupport portion secured to an end face of said rotatable gear.
 7. Theinvention as described in claim 1, further comprising an end bushingsupported within said housing and secured to a further and interiorlyextending end of said drive rod, an exposed face of said end bushingbiasing said spring in a compressing coiled fashion.
 8. The invention asdescribed in claim 7, further comprising a spacer washer sandwichedbetween said exposed face of said end bushing and a terminating coil ofsaid spring.
 9. The invention as described in claim 1, said detentfurther comprising a “U” shaped rigid wire secured to an extendingunderside surface of said trigger mechanism.
 10. A linear reclinerassembly in use with a seat, the seat having a frame supporting apivotal seat back relative to a seat bottom, the seat bottom including arotating coupling exhibiting a threaded interior and which is mounted toa side location of the frame, the seat back including a lower mostportion extending below a pivot about which the seat back rotates, saidrecliner assembly comprising: an elongate and three dimensional housinghaving a communicating interior between a first end and a second end ofsaid housing; a drive rod supported in linearly displaceable fashionwithin said housing, said drive rod extending from said first end andbeing threadably displaceable through the interior of the rotatingcoupling; said second end of said housing pivotally engaged to the lowermost portion of the seat back; said housing further comprising a centraltubular portion, a first end cap secured to a first end of said centraltubular portion, said first end cap exhibiting a central opening throughwhich extends said drive rod, a second end cap secured to a second endof said central tubular portion, said second end cap terminating infirst and second spaced apart mounting portions and, upon aligning saidmounting portions with the pivotally engaged location of the seat back,a pin being received in laterally inserting fashion for pivotallymounting said second end cap to the seat back; said central tubularportion further comprising a linear recess extending from said firstend, a secondary housing coaxially inserting within said central tubularportion from said first end, said secondary housing further comprising atrigger support projecting from said linear recess; a rotatable gearlocated at a fixed lineal position within said housing and through whichsaid drive rod is threadably inter-engaged, a thrust bearing beingarranged at each of opposite sides of said rotatable gear; a triggermechanism pivotally secured to said trigger support and exhibiting adownwardly biased detent communicating through an opening in saidhousing to seat between succeeding teeth of said gear; a cableattachment bracket secured to said housing in proximity to said triggermechanism, a cable exhibiting an outer sheath and which is affixed tosaid cable attachment bracket, an inner translating portion extendingfrom said outer sheath and engaging a clip secured to said triggermechanism; and a coil spring supported within said housing interior, anend bushing supported within said housing and secured to a further andinteriorly extending end of said drive rod exhibiting an exposed facebiasing said spring in a compressing coiled fashion; upon release ofsaid detent from said gear, an external reclining force applied to theseatback results in displacement of said housing against said drive rodto compress said spring, said spring influencing the drive rod in areverse direction such that, upon release of said detent from said gearwhen the seatback is in the reclined position, said spring influencingthe seat back to reverse pivot to a returned upright position.
 11. Theinvention as described in claim 10, further comprising a pair of torsionsprings seated in opposing fashion upon a pivot location establishedbetween said trigger mechanism and said trigger support, said springincluding an extending leg biasing said detent toward said gear teeth.12. The invention as described in claim 10, further comprising at leastone support bushing arranged in linearly positioned and end facingcontact with a selected one of said thrust bearings.
 13. The inventionas described in claim 12, further comprising a cylindrical shaped drivesupport portion secured to an end face of said rotatable gear.
 14. Theinvention as described in claim 10, further comprising a spacer washersandwiched between said exposed face of said end bushing and aterminating coil of said spring.
 15. The invention as described in claim10, said detent further comprising a “U” shaped rigid wire secured to anextending underside surface of said trigger mechanism.
 16. A linearrecliner assembly in use with a seat, the seat having a frame supportinga pivotal seat back relative to a seat bottom, the seat bottom includinga rotating coupling exhibiting a threaded interior and which is mountedto a side location of the frame, the seat back including a lower mostportion extending below a pivot about which the seat back rotates, saidrecliner assembly comprising: a housing having an open interiorextending between a first end and a second end of said housing; a driverod supported in linearly displaceable fashion within said housing, saiddrive rod extending from said first end of said housing in threadablydisplaceable fashion through the rotating coupling; said second end ofsaid housing terminating in an end cap which is pivotally engaged to thelower most extending portion of the seat back; said housing furthercomprising a linear recess extending from said first end, a secondaryhousing coaxially inserting within said first end, said secondaryhousing further comprising a trigger support projecting from said linearrecess; a rotatable gear located at a fixed lineal position within saidhousing, said gear being internally threaded for receiving therethroughsaid drive rod; a trigger mechanism pivotally secured to said triggersupport and exhibiting a downwardly biased detent communicating throughan opening in said housing to seat between succeeding teeth of saidgear; and a spring supported within said housing interior in contactwith an end bushing displaceably secured to an internally extending endof said drive rod; upon release of said detent from said gear, anexternal reclining force being applied to the seatback resulting indisplacement of said housing against said drive rod to bias said spring,said spring influencing the drive rod in a reverse direction such that,upon release of said detent from said gear when the seat back is in thereclined position, said spring influencing the seatback to reverse pivotto a returned upright position.